Process for improving the dyeability of shaped structures of polyesters based on terephthalic acid



PROCESS FOR 11VIPROVING THE DYEABILITY F SHAPED STRUCTURES OF POLYESTERS BASED ON 'IEREPHTHALIC ACID Adolf Hartmann, Gessertshausen, near Augsburg, Wilhelm Happe, Schwalbach (Taunus), and Gerhard Gatys, Bohingen, near Augsburg, Germany, assignors to Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius & Briining, Frankfurt am Main, Germany, a corporation of Germany No Drawing. Filed Mar. '5, 1957, Ser. No. 643,947 Claims priority, application Germany Mar. '10, 1956 3 Claims. (Cl. 8-115.5)

In general, linear polyesters based on terephthalicacid and shaped structures thereof such as fibers, filaments: or foils, show a low absorptivity for dyestuffs present in the form of an aqueous solution or dispersion. It is known to improve the dyeability ofthe polyesters mentioned above as well as that of the goods produced thereof by treating the shaped articles of polyesters with vapours of sulfuric acid, sulfuric anhydride or chloro-sulfonic acid.

The shaped fibers, filaments or foils obtained according to this method, exhibit however, considerable disadvantages. The improvement in the dyeability reached by the known process is often unsatisfactory and insufiicient for many purposes. Moreover, the dyeings obtained in this way are more or less dull and not fast to rubbing. It is true that the depth of shade can be'improved, when the vapours mentioned above are caused to act upon the goods at an elevated temperature, for instance at 50 C. Apart from the fact that also with this method of operation the fastness to rubbing of the colored materials is insufiicient, the application of the elevated temperatures often gives rise to stained tints which are caused in the gaseous phase by the unequal heating of the material to be dyed. It must be mentioned that each form of humidity is to be excluded, a fact which also causes technical difficulties. A higher concentration of chloro-sulfonic acid or sulfuric anhydride in the gas volume in order to obtain a more intense and more uniform dyeing canbe reached only to a restricted extent, since these compounds are increasingly precipitated on the fibrous material whereby heavy damages of the latter are provoked.

Now, we have found that these drawbacks can be avoided and that it is possible to obtain shaped structures, particularly fibers and filaments of polyesters based on terephthalic acid, before all those of polyethylene glycol terephthalate, which, without application of carriers or printing apparatus can be dyed in a simple and satisfactory manner and are absolutely fast to rubbing, and whose resistance is practically not or only insignificantly reduced in comparison with the non-treated goods, by treating the structures with addition products of ethers or tertiary amines, with sulfur trioxide and/ or halides of sulfur oxygen acids in the presence of inert solvents.

Such halogen compounds of sulfur oxygen acids are, for instance, halogenated sulfonic acids such as chlorosulfonic acid and fluorosulfonic acid, sulfuryl chloride, pyro-sulfuryl chloride, thionyl chloride. For the formation of the addition products each of the above-mentioned substances can be used per se or in admixture with each other; for this purpose sulfur trioxide can also be added.

As appropriate ethers for the formation of addition products there enter into consideration, for instance, aliphatic and cyclic ethers, such as B.[3'-dichloro-diethylether, tetrahydrofurane, dioxane and thioxane. As tertiary amines there may be mentioned, for instance, aliphatic amines, such as trimethyl-amine or triethyl-amine; aromatic amines, such as N.N-dimethyl-aniline; heterocyclic compounds, for instance pyridine. Whereas the ethers offer the advantage of intensifying the reaction btates atent O whereby a particularly good dyeing activation is reached, the addition of tertiary amines causes a smoother but very uniform reaction which in the dyeing process results in particularly uniform and clear shades. The amount of ethers or amines added generally corresponds to the molar proportions known for the addition products: For'example one or two mols of sulfur trioxide or chlorosulfonic acid being applied for one mol of ether or tertiary amine. It is, however, possible to add the ethers or amines in any other quantity, particularly in a higher amount than is necessary for forming the addition products.

As solvents there enter into consideration, before all, carbon halides, such as chloroform, trichloro-ethane, tetrachloro-ethane, methylene chloride and ethylene chloride being particularly suitable. Mixtures of these solvents can also be used.

The concentration of the solutions containing the addition products may vary in wide limits. In general, solutions of 0.01% to 1%, preferably of 0.05 to 0.5% strength, are used. When the reactive compounds are'used in admixture with each other the desired effect can be improved, if necessary. There are particularly favorable, for instance, mixtures of chlorosulfonic acid and sulfuryl chloride in a ratio of 1:1 or of chloro sulfonic acid and sulfur trioxide in a ratio of 1:2.

The shaped structures can be treated with the reaction solutions at the ordinary or at an elevated temperature; the period of action may vary within wide limits, for instance between 2 and 60 minutes. A preferred method of operation consists in allowing the solutions to act upon the structures at the boiling temperature of the solvent and with reflux. By means of suitable apparatus it is also possible to operate continuously, for instance at the running spinning cable. In this case it is necessary to add the reactive compounds according to their consumption.

After the good'shave been treated, they are centrifuged or squeezed and additionally washed with suitable solvents. For this purpose low aliphatic alcohols or ketones, such as methanol or acetone enter into consideration. It is, however, also possible and practically of high advantage to wash the structures by means of warm water to which an emulsifying substance, for instance a phenolpolyglycol ether has been added in a concentratio'njof, for instance, 0.5 to 1 gram/ liter. The structure is then thoroughly rinsed again with warm water.

The structures treated in this way, particularly fibers and filaments, as regards appearance and textile properties were either not altered or only favorably, in comparison with the initial material. They can easily be dyed under the usual conditions with numerous basic dyestuffs, and particularly with dispersion dyestuffs, for instance with a red dyestutf mixture consisting of 50% of a dyestutf corresponding to the formula $113 0 O OrN N N and 50% of a red dyestuff corresponding to the formula ChzCHrOH CHHCHQOH 3 thraquinone and 15.5% of a dycstuff corresponding to the formula or with a black dyestufi of the following composition:

15.25% of 1.4.5.8 -tetra-amino-anthraquinone, partly methylated,

47.5% of 1.4-diamino-anthraquinone, partly methylated,

17.75% of p-nitro-amino-azobenzene,

16.5% of 1.4-dihydroxy-ethyl-S.8-dihydroxy-anthraquinone,

3.0% of a dyestutf according to the formula The dyeings obtained are clear, absolutely fast to rubbing and of very high fastness to light. The dyeings are also widely resisting to normal washing with soap.

It is of advantage to wash again with aqueous ammonia, suitably with a concentrated ammonia solution.

Following the treatment described above it is, however, most advantageous to treat the polyester material additionally with hydrazine solutions or with N-formyl compounds which still contain a reactive hydrogen atom.

In order to reduce costs and avoid difficulties Water will preferably be used as solvent. It is, however, also possible to apply other appropriate solvents, for instance aliphatic alcohols, such as methanol, ethanol or their mixtures with water.

Naturally, the further treatment with the hydrazine solutions must be carried out under such conditions that the properties of the shaped articles be not injuriously affected, i.e. the duration of the treatment, the temperature and the concentrations must be chosen low enough that no deterioration of the material occurs.

In general, it is sufiicient that at temperatures of 60 to 100 C., preferably between 80 and 95 C., the solutions act upon the material for about 2 to 5 minutes. The period of time indicated above depends upon the concentration of the hydrazine. When applying a temperature of about 95 C. and a period of action of 2 to 3 minutes, a concentration of 1 to 2% referred to the bath will, in general, be suflicient. When lower temperatures are chosen, the period of action must be prolonged.

The shaped articles thus treated and dyed show good fastness to ironing, moreover, the shades of the dyeings are well resistant to elevated temperatures.

When using instead of hydrazine N-formyl compounds containing at least one hydrogen atom at the nitrogen atom carrying the formyl group for the further treatment, the same improvement can be realised.

As such N-formyl compounds there may be mentioned, for instance, formamide and its derivatives substituted by aliphatic, cyclo-aliphatic, araliphatic radicals, e.g. ethylformamide, cyclo-hexylformamide, benzyl-formamide, di- (N formyl)-ethylene-diamine, di(N-formyl)-hexamethylene-diamine. These compounds are preferably used in a dilute state, i.e. in solution. As solvents those compounds are used as under the test conditions do not react with a formyl group, for instance aliphatic alcohols, such as methanol or ethanol, ketones, such as acetone, ethers, such as diethyl ether, esters, such as ethyl acetate, aliphatic or cycloaliphatic hydrocarbons, such as hexane, cyclo-hexane or mixtures, such as light gasoline, carbon halides, such as carbon tetrachloride, chloroform, methylene chloride or ethylene chloride. As solvent water is preferred in order to reduce the costs.

Generally, the further treatment is carried out at an elevated temperature, usually in the boiling solution. The concentration of the solutions may vary within wide limits; it depends on the chemical constitution of the formyl compounds, on the duration of the treatment, on the temperature applied and on the effect desired. Generally, the concentration will be chosen so high that the period of treatment is within the favorable range of a continuous manufacture. Preferably aqueous solutions of 0.1 to 10% strength, preferably of 0.5 to 5% strength will be used. In this case a period of treatment amounting to 2 to 5 minutes will be sufficient when a temperature of about 98 to 100 C. is applied. With lower temperatures the period of treatment must be prolonged or the concentration must be increased.

Naturally, it is possible to use various formyl compounds simultaneously and to add to the baths substances which in a known manner act as swelling agents, for instance phcnyl-glycol, cresyl-glycol, dioxane, benzyl benzoate. If necessary, an appropriate emulsifier can be used simultaneously.

The following examples serve to illustrate the invention but they are not intended to limit it thereto:

Example 1 20 grams of a stretched staple fiber of polyethylene glycol terephthalate having a single titer of 3 deniers are treated for 6 minutes under reflux at the boiling temperature with a solution of 3 grams of chlorosulfonic acid and 2.4 grams of dioxane in 1000 cc. of ethylene ch1oride. The solution is then separated off, the fiber is centrifuged for a short time and washed with about 2 liters of water of 50 C. to which 0.5 gram-liter of a phenol-poly-glycol ether with 20 units of ethylene-oxide had been added. Finally, the fibers are rinsed with handwarm water and dried.

The resistance of the fiber is practically not reduced; it can be dyed deep shades by means of dispersion dyestuffs. With a dyestuff mixture consisting of 50% of a red dyestufi corresponding to the formula CHzCHzOH and 50% of a red dyestufi corresponding to the formula a dark red tint is obtained by dyeing the fiber for minutes at the boil with an amount of dyestutf amounting to 4% of the weight of the fiber. After dyeing the fiber is rinsed with warm water and dried. The dyed material is well resistant to rubbing and washing at the boil.

Example 2 1.35 grams of pyridine are added to 300 cc. of ethylene chloride, a solution of 2.0 grams of chlorosulfonic acid in 200 cc. of ethylene-chloride is then added thereto, while stirring. 10 grams of the staple fiber mentioned in Example 1 and consisting of polyethylene glycol terephthalate are introduced into this solution, and the whole is heated to boiling for 10 minutes. The fiber is then separated and washed as described in Example 1.

The dyeings obtained with dispersion dyestuffs are very uniform, the shades are extremely clear and brilliant.

Example 3 44 grams of dioxane and 40 grams of sulfur trioxide are added to 10 liters of dry ethylene-chloride. With this solution 200 grams of spinning cable of polyethyleneglycol terephthalate having a total titer of 75,000 deniers and a resistance to breaking of the single filament of 4.8 grams-denier are treated for 5 minutes at the temperature '5 of reflux. The cable is then squeezed E and :washed with water of 50 C. containingper liter 0.5 gram of a phenol-polyglycol ether obtained by reaction ofthe phenol with 20 mols of ethylene oxide. The cable is then thoroughly rinsed with warm water and dried. After this treatment the spinning cable shows an agreeable, soft feeling, the resistance of the single filament amounts to 4.3 grams/denier. Without the application ofswelling agents or superatmospheric pressure the cable canbe dyed deep brilliant shades with numerous dispersion dyestulfs, for instance with an amount of a dyestuff mixture of 46% of the weight of the fiber and consisting of 0% of a red dyestuff corresponding to the formula CHzCHgOH and 50% of a red dyestuff corresponding to the formula or with 4 to 6% of a dyestufi mixture consisting of OHg.CH2OH l CzHs CHr-CHgOH 20.0% of a condensation product from cresol, formaldehyde and sodium sulfite, which was further heated with B-naphtholic acid formaldehyde and sulfite,

20.0% of a pulverized, neutralized waste product of sulfite cellulose,

4.0% of sodium dibutyl-naphthalino-sulfonate,

16.0% of Glauber salt.

The cable is to be dyed with this dyestutt-mixture for 1 /2 hours at the boiling temperature.

Instead of dissolving sulfur trioxide and dioxane successively in ethylene chloride it is also possible to produce at first in a known manner the chemically defined addition products from 1 or 2 mols of sulfur trioxide and 1 mol of dioxane and to add these products to the solvent.

Example 4 50 grams of sulfur trioxide are dissolved in 300 cc. of dry ethylene chloride. While stirring at 20 C., a solution of 55.1 grams of dioxane in 533 cc. of ethylene chloride is added to the first-mentioned solution.

680 cc. of the solution thus obtained are diluted with 4320 cc. of ethylene chloride, and 100 grams of staple fiber 3/100 of polyethylene glycol terephthalate are introduced into the solution. The whole is heated for 5 minutes under reflux, care being taken that the fiber is always covered by the solution. Decantation then takes place, the fiber is centrifuged and treated for three minutes at 98 C. with an aqueous hydrazine hydrate solution of 2% strength. The fiber is then centrifuged again, washed several times with water of 40 to 50 C. and dried.

The fiber obtained in this way can be dyed deep shade, with good fastness properties with several dispersion dye- 6 "stufls, for instance with the dyestufii fromamino-azobeuzene o-cresolor the dyestuflf of the'following formula NHz N NHI Example 5 A stretched spinning cable of polyethylene glycol terephthalate with a total titer of 20,000 deniers, previously treated with the addition product from dioxane and sulfur trioxide in methylene chloride according to the process disclosed above, is passed at 98 C. through an aqueous solution of 5% strength of formamide with such a velocity that the period of staying in the solution amounts to 3 minutes. The fiber is then rinsed for a short time with water of room temperature, prepared in the usual manner and dried. After curling and cutting a fiber flock is obtained which can be dyed deep shades and with good fastness properties by means of numerous dispersion dyestuffs without using swelling agents or superatmospheric pressure. The shades of the dyeings correspond to those obtained on non-treated material by means of swelling agents or at dyeing temperatures superior to 100 C. The dyeings are resistant to heat and show a good fastness to light.

Example 6 A fiber flock of polyethylene glycol terephthalate (single titer 3 den.) whose dyeability has been improved in the abovedescribed manner by treatment with an addition product of dioxane and sulfur trioxide is then further treated for 3 minutes at C. with an aqueous solution of 3% strength of N-formyl-cyclo-hexylamine. The flock is then rinsed with water and dried. It canbe easily dyed with dispersion dyestuffs, the dyeings possessing good resistance to heat and showing a good fastness to light.

Example 7 A spinning cable of polyethylene glycol terephthalate whose dyeability has been improved in the above-disclosed manner by treatment with an addition product of dioxane and sulfur trioxide is treated for 5 minutes at the temperature of reflux with a solution of 2% strength of ethyl formamide in ethylene chloride. The cable is dried in a stream of hot air and treated as described in Example 5. The fiber obtained is characterized by a very good dyeability with numerous dispersion dyestuffs. The dyeings are resistant to ironing and conform with the type of shade.

We claim:

1. In a process for improving the dyeability of shaped structures of linear polyesters based on terephthalic acid by treating them with a compound selected from the group consisting of sulfur trioxide and halogenated sulfonic acids, the improvement which comprises treating the structures with a solution in an inert solvent of addi tion products selected from the group consisting of addition products of an ether with sulfur trioxide, of an ether with a halide of a sulfur oxygen acid, of an ether with a mixture of sulfur trioxide and a halogenated sulfonic acid, of a tertiary amine with sulfur trioxide, of a tertiary amine with a halogenated sulfonic acid and of a tertiary amine with a mixture of sulfur trioxide and a halogenated sulfonic acid.

2. A process as claimed in claim 1, wherein an addition product of dioxane and sulfur trioxide is used.

3. A process as claimed in claim 1, wherein a low molecular chlorinated aliphatic hydrocarbon is used as solvent for the addition product.

4. A process as claimed in claim 1, wherein methylene chloride is used as solvent for the addition product.

5. A process as claimed in claim 1, wherein the process is carried out at an elevated temperature.

6. A process as claimed in claim 1, wherein the treated material is aftertreated with a hydrazine material.

7. A process as claimed in claim 1, wherein the treated material is aftertreated with N-formyl compounds, which still contain a reactive hydrogen atom.

8. Polyethylene terephalate modified by treatment with an addition product of components selected from the group consisting of (A) an ether and a tertiary amine with a member of the group consisting of (B) sulfur trioxide, a halogenated sulfonic acid, and a mixture of sulfur trioxide and a halogenated sulfonic acid.

1 References Cited in the file of this patent UNITED STATES PATENTS 2,647,104 Shivers July 28, 1953 2,849,458 Walker Aug. 26, 1958 2,852,554 England Sept. 16, 1958 FOREIGN PATENTS 613,817 Great Britain Dec. 3, 1948 613,818 Great Britain Dec. 3, 1948 OTHER REFERENCES Somers: Improving the Dyeing Properties of Polyester Fibres, British Rayon and Silk Journal, February 1954, pp. 56-57.- 

1. IN A PROCESS FOR IMPROVING THE DYEABILITY OF SHAPED STRUCTURES OF LINEAR POLYESTERS BASED ON TEREPHTHALIC ACID BY TREATING THEM WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SULFUR TRIOXIDE AND HALOGENATED SUL FONIC ACIDS, THE IMPROVEMENT WHICH COMPRISES TREATING THE STRUCTURES WITH A SOLUTION IN AN INERT SOLVENT OF ADDITION PRODUCTS SELECTED FROM THE GROUP CONSISTING OF ADDITION PRODUCTS OF AN ETHER WITH SULFUR TRIOXIDE, OF AN ETHER WITH A HALIDE OF A SULFUR OXYGEN ACID, OF AN ETHER WITH A MIXTURE OF SULFUR TRIOXIDE AND A HALOGENATED SULFONIC ACID, OF A TERTIARY AMINE WITH SULFUR TRIOXIDE, OF A TERTIARY AMINE WITH A HALOGENATED SULFONIC ACID AND OF A TERTIARY AMINE WITH A MIXTURE OF SULFUR TRIOXIDE AND A HALOGENATED SULFONIC ACID. 